Some of these may have been said already and I'm sorry if this is the case

Scuffle Island (IL): Very self explanatory, beat all of the Scuffle Island Paper Macho bosses. Timing starts when closing the last text box before the challenge begins and timing ends when landing the final hit on Paper Macho Buzzy Beetle

Boss Rush (Miscellaneous): Fight through all of the Bossotronic rematches in order. Timing starts when choosing the Earth Vellumental boss fight and ends when landing the final hit on Stapler (No Paper macho rematches since Scuffle Island exists for that)

The Ringer Rush (Miscellaneous): Complete all 3 levels of The Ringer as fast as possible. Timing starts when selecting level 1 and ends when completing the final ring puzzle in level 3

Red Streamer (IL): Start the game and clear the red streamer. Timing starts when selecting an empty save file and ends when landing the final hit to smash the Olly seal on the streamer

Blue Streamer (IL): Continue after clearing the red streamer until clearing the blue streamer. Timing starts when closing the final text box before entering the tram to Overlook Mountain and ends when landing the final hit to smash the Olly seal on the streamer

Yellow Streamer (IL): Continue after clearing the blue streamer until clearing the yellow streamer. Timing starts when closing the final text box before heading to Sweet Paper Valley with Sculler Toad and ends when landing the final hit to smash the Olly seal on the streamer

Purple Streamer (IL): Continue after clearing the yellow streamer until clearing the purple streamer. Timing starts when activating the Fire Vellumental Magic Circle to save T. Ode and ends when landing the final hit to smash the Olly seal on the streamer (Timing start can be debated but I believe rescuing T. Ode is when the purple streamer adventure starts)

Green Streamer (IL): Continue after clearing the purple streamer until clearing the green streamer. Timing starts when entering the pillar of light that allows you to reach Shangri-Spa and ends when landing the final hit to smash the Olly seal on the streamer

Finale (IL): Continue after clearing the green streamer until defeating Olly. Timing starts when entering Bowser's Airship and ends when closing the final text box, from Luigi

100% is self-explanatory. 3 star ranks on all cups of the engine modes in Grand Prix (100 and 50 can be skipped since 3 star ranks in 150 get applied to both automatically), beat all the 150cc and 200cc staff ghosts to get the gold tires and collect 5k coins to get all the vehicle parts and the Gold Glider (Quick update to 100%: It may include 200cc staff ghosts instead of not including them) 99% is the same except you only get 3.1k coins and skip the Gold Glider

Some extra rules would be being able to take small breaks but still counting towards the final time, considering 99% alone is already over 10 hours long on average, and having to show yourself creating the new profile to know of its legitimacy

Timing starts when selecting the newly created user to play the game with and ends when showcasing the last vehicle part being obtained (the Gold Glider in 100% and whatever the last vehicle part you obtain is in 99%)